Eukaryotic Cell
Eukaryotic Cell Definition Eukaryotic cells are cells that contain a nucleus and organelles, and are enclosed by a plasma membrane. Organisms that have eukaryotic cells include protozoa, fungi, plants and animals. These organisms…
Cell Structure and Function
All living things are composed of cells. Cells are the basic units of life and all tissues and organs are composed of cells. They are so small that they must…
Coupled Reactions
Two or more reactions in a cell sometimes can be coupled so that thermodynamically unfavorable reactions and favorable reactions are combined to drive the overall process in the favorable direction.…
Second Law of Thermodynamics: Entropy
The second law of thermodynamics states that the universe (i.e. all systems) tend to the greatest degree of randomization. This concept is defined by the term entropy, S. S = klnW where k =…
First Law of Thermodynamics
Stated simply; The total energy of the universe does not change. This does not mean that the form of the energy cannot change. Indeed, chemical energies of a molecule can…
Kinetic Isotope Effects
The kinetic isotope effect (KIE) is a phenomenon associated with isotopically substituted molecules exhibiting different reaction rates. Isotope effects such as KIEs are invaluable tools in both physical and biological sciences and are…
Kinetic Versus Thermodynamic Products
Kinetic products form the fastest. They usually occur at or below 0°C. This is also known as the 1,2-adduct because the substituents are added to the first and second carbons.…
The Principle of Microscopic Reversibility
The principle of microscopic reversibility applies to any molecular process; it is inferred from the fact that such processes can be described by their equations of motion if the initial…
Definition of a Reaction Intermediate
What exactly is a reaction intermediate? A reaction intermediate is formed from the reactants in a chemical reaction, and reacts further to produce the products observed after the reaction is complete. Let's…
Transition state
The transition state of a chemical reaction is a particular configuration along the reaction coordinate. It is defined as the state corresponding to the highest potential energy along this reaction coordinate. It is often marked with…
